(1) Field of the Invention
The present invention relates to a support board separating apparatus for separating, from a semiconductor wafer, a support board such as a glass substrate held while being joined to the semiconductor wafer through a double-faced adhesive tape, and a support board separating method using the same.
(2) Description of the Related Art
Generally, a semiconductor wafer is subjected to a process for forming a circuit pattern of a large number of elements on a surface thereof, and then is subjected to a back grinding process for grinding or polishing a back face thereof so as to have a desired thickness. Thereafter, the semiconductor wafer is subjected to a dicing process for cutting it into plural elements.
In recent years, there has been demanded a thin semiconductor wafer as an application is rapidly progressed. A requested thickness of the semiconductor wafer is 100 μm to 50 μm, in some cases, about 25 μm. Such a thin semiconductor wafer is brittle and is readily bent; therefore, its handleability is extremely poor. In order to solve this problem, for example, a support board with high strength, such as a glass substrate, is joined to a surface of a semiconductor wafer through a double-faced adhesive sheet so as to hold the semiconductor wafer, and the semiconductor wafer is subjected to backing reinforcement with the use of the support board. Thereafter, a back face of the semiconductor wafer is subjected to a back grinding process. After completion of the process, the semiconductor wafer is separated from the support board.
Conventionally, JP-A 2001-7179 discloses a method for separating, from a semiconductor wafer, a support board joined to the semiconductor wafer through a double-faced adhesive sheet so as to hold the semiconductor wafer.
More specifically, a double-faced adhesive sheet to be used is of an ultraviolet-ray curable type in which its adhesion force is lowered by irradiation of ultraviolet rays. First, the adhesion force is previously lowered by irradiation of ultraviolet rays. Next, a semiconductor wafer is heated in a state that the semiconductor wafer is held and sucked by vacuum by upper and lower tables, and the double-faced adhesive sheet is allowed to contract and deform, so that a contact area between the double-faced adhesive sheet and the semiconductor wafer becomes small; thus, the semiconductor wafer is floated. Then, after end of the contraction and completion of peeling of the double-faced adhesive sheet, the suction by the upper table is released and the upper table is retreated upward. Thereafter, in a state that the semiconductor wafer is sucked by and fixed at the lower table, a holding member is moved while being sucked by a transporting arm; thus, the double-faced adhesive sheet is peeled off from the semiconductor wafer. Herein, in addition to the ultraviolet-ray curable double-faced adhesive sheet, a heat-peelable double-faced adhesive sheet may be used. The heat-peelable double-faced adhesive sheet is foamed by heating, so that its adhesion force is lowered.
The aforementioned separating method performs various processes for moving a table suction-holding a workpiece along a long movement path to thereby separate a member such as a support board from a semiconductor wafer. Therefore, the size of an apparatus is increased and, also, it takes much time to stably move a table over respective processing sections. Consequently, there arises a problem that it is difficult to efficiently separate and collect a semiconductor wafer and a support board.